CVE-2020-29583

Name: CVE-2020-29583
Creator: NVD / NIST
Published: 2020-12-22T22:15:14.443+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 90.05%

Last modified Jun 17, 2026

CVE-2020-29583 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the firmware. CISA has confirmed active exploitation in the wild. EPSS estimates a 90.05% chance of exploitation in the next 30 days.

Description

Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the firmware. This account can be used by someone to login to the ssh server or web interface with admin privileges.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

90.05%

99.8th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by May 3, 2022.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Zyxel	Usg20-Vpn Firmware	4.60
Zyxel	Usg20w-Vpn Firmware	4.60
Zyxel	Usg40 Firmware	4.60
Zyxel	Usg40w Firmware	4.60
Zyxel	Usg60 Firmware	4.60
Zyxel	Usg60w Firmware	4.60
Zyxel	Usg110 Firmware	4.60
Zyxel	Usg210 Firmware	4.60
Zyxel	Usg310 Firmware	4.60
Zyxel	Usg1100 Firmware	4.60
Zyxel	Usg1900 Firmware	4.60
Zyxel	Usg2200 Firmware	4.60
Zyxel	Zywall110 Firmware	4.60
Zyxel	Zywall310 Firmware	4.60
Zyxel	Zywall1100 Firmware	4.60
Zyxel	Atp100 Firmware	4.60
Zyxel	Atp100w Firmware	4.60
Zyxel	Atp200 Firmware	4.60
Zyxel	Atp500 Firmware	4.60
Zyxel	Atp700 Firmware	4.60
Zyxel	Atp800 Firmware	4.60
Zyxel	Vpn50 Firmware	4.60
Zyxel	Vpn100 Firmware	4.60
Zyxel	Vpn300 Firmware	4.60
Zyxel	Vpn1000 Firmware	4.60
Zyxel	Usg Flex 100 Firmware	4.60
Zyxel	Usg Flex 100w Firmware	4.60
Zyxel	Usg Flex 200 Firmware	4.60
Zyxel	Usg Flex 500 Firmware	4.60
Zyxel	Usg Flex 700 Firmware	4.60

References

http://ftp.zyxel.com/USG40/firmware/USG40_4.60%28AALA.1%29C0_2.pdfBroken Link
https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-releaseRelease Notes
https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15Release Notes
https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.htmlBroken Link, Third Party Advisory
https://www.secpod.com/blog/a-secret-zyxel-firewall-and-ap-controllers-could-allow-for-administrative-access-cve-2020-29583/Exploit, Third Party Advisory
https://www.zyxel.com/support/CVE-2020-29583.shtmlVendor Advisory
https://www.zyxel.com/support/security_advisories.shtmlVendor Advisory
http://ftp.zyxel.com/USG40/firmware/USG40_4.60%28AALA.1%29C0_2.pdfBroken Link
https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-releaseRelease Notes
https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15Release Notes
https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.htmlBroken Link, Third Party Advisory
https://www.secpod.com/blog/a-secret-zyxel-firewall-and-ap-controllers-could-allow-for-administrative-access-cve-2020-29583/Exploit, Third Party Advisory
https://www.zyxel.com/support/CVE-2020-29583.shtmlVendor Advisory
https://www.zyxel.com/support/security_advisories.shtmlVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-29583US Government Resource

Timeline

Published: Dec 22, 2020
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2020-29583?

How severe is CVE-2020-29583?

CVE-2020-29583 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 90.05% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2020-29583?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-29583?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST